588
U N I T 6
Respiratory Function
respiratory symptoms (shortness of breath, nonpro-
ductive cough, chest pain) or constitutional signs and
symptoms (e.g., fever, sweating, anorexia, weight loss,
fatigue, myalgia). Eye involvement (anterior uveitis) and
skin involvement (skin papules and plaques) are partic-
ularly common extrathoracic manifestations, but there
may be cardiac, neuromuscular, hematologic, hepatic,
endocrine, and lymph node findings.
Sarcoidosis is characterized by either progressive
chronicity or periods of activity interspersed with remis-
sions, sometimes permanent, that may be spontaneous
or induced by corticosteroid therapy. Approximately
65% to 75% of persons recover with minimal clinical
and radiographic abnormalities.
15
Other persons have
persistent radiographic abnormalities and progression
of their respiratory symptoms, with or without addi-
tional extrathoracic disease.
The diagnosis of sarcoidosis is based on history and
physical examination, tests to exclude other diseases,
chest radiography, and biopsy to obtain confirmation of
noncaseating granulomas. A thorough ophthalmologic
evaluation is recommended for most persons, even those
without ocular symptoms.
Treatment is directed at interrupting the granuloma-
tous inflammatory process that is characteristic of the
disease and managing the associated complications.
When treatment is indicated, corticosteroid drugs are
used. These agents produce clearing of the lung, as seen
on the chest radiograph, and improve pulmonary func-
tion, but it is not known whether they affect the long-
term outcome of the disease.
SUMMARY CONCEPTS
■■
The interstitial lung diseases are a diverse
group of lung disorders that produce similar
inflammatory and fibrotic changes in the
interstitium or alveolar septa of the lung. As
a result, the lungs become stiff and difficult
to inflate, increasing the work of breathing
and causing dyspnea and decreased exercise
tolerance due to hypoxemia, without evidence of
wheezing or signs of airway obstruction.
■■
These diseases include drug- and radiation-
induced lung disease, environmental and
occupational lung diseases caused by inhalation
of organic and inorganic dusts, immunologic
lung disorders such as those that accompany
scleroderma, idiopathic pulmonary fibrosis, and
sarcoidosis.
■■
The restrictive lung disorders reduce the diffusing
capacity of the lung, producing various degrees
of hypoxemia, dyspnea, tachypnea, and eventual
cyanosis.
FIGURE 23-13.
Pulmonary embolism. The main pulmonary
artery and its bifurcation have been opened to reveal a
large saddle embolus. (From McManus BM, Allard MF,
Yanagawa R. Hemodynamic disorders. In: Rubin R, Strayer
DS, eds. Rubin’s Pathology: Clinicopathologic Foundations of
Medicine. 6th ed. Philadelphia, PA: Wolters Kluwer Health |
Lippincott Williams &Wilkins; 2012:275. Courtesy of Dr. Greg
J. Davis.)
Disorders of the Pulmonary
Circulation
As blood moves through the pulmonary capillaries,
the oxygen content increases and the carbon dioxide
decreases. These processes depend on the matching
of ventilation (i.e., gas exchange) and perfusion (i.e.,
blood flow). This section discusses two major prob-
lems of the pulmonary circulation: pulmonary embo-
lism and pulmonary hypertension. Pulmonary edema,
another major problem of the pulmonary circulation, is
discussed in Chapter 20.
Pulmonary Embolism
Pulmonary embolism develops when a blood-borne
substance lodges in a branch of the pulmonary artery
and obstructs blood flow.
15,16,59,61
The embolism may
consist of a thrombus (Fig. 23-13), air that has acci-
dentally been injected during intravenous infusion, fat
that has been mobilized from the bone marrow after a
fracture or from a traumatized fat depot, or amniotic
fluid that has entered the maternal circulation during
childbirth.
